Conventional HMDs use a single screen that is visible to both eyes of a user. A conventional HMD can be used to display a virtual world to a user. Single screen HMDs limit the FOV of a user to around 110°. Attempts to increase the immersivity experienced by a user by providing a FOV over 180° have been large and expensive. The increase in size and expense of wider FOV HMDs arises partly because the optical components are often larger or more numerous. As a result, size and cost deter the adoption and regular usage of panoramic HMDs, leaving users limited to a virtual world where they can see far less than their eyes can see.
Several conventional approaches have been described for HMDs that provide a narrow FOV using a single screen visible to both eyes of a user. In one approach, US 2017/0212360 (Yang et al.) describes a large, single lens, a pair of polarizers, and a pair of prisms that can allow both eyes to see the same part of a screen displaying two polarized images. In another example, U.S. Pat. No. 9,769,465 (Seo et al.) describes an HMD design in which a curved autostereoscopic screen is viewed by both eyes through a large, single lens. In yet another approach, U.S. Pat. No. 5,754,344 (Fujiyama) describes an autostereoscopic screen, placed near the forehead of a user that can be seen by both eyes when the light is reflected off a large concave mirror. In another approach, JP 10206786A (Kanayama) describes a system with two concave mirrors and two flat half silvered mirrors in the optical paths. US 2017/0347089 (C. Peterson) describes the general case of using an autostereoscopic screen in a virtual reality or augmented reality system.
Conventional approaches to provide a panoramic FOV over 110° increase the number, size, and complexity of optical components and screens. In some examples, two or more screens may be used instead of one. EP 2564259B1 (Cheng et al.) describes an HMD with tiled TIR prisms that may be used with several micro-displays to provide a wide FOV. In other examples, lenses are widened, stacked or fused. US 2017/0115489 (Hu et al.) describes a system in which one curved screen and two fused lenses are needed for each eye to provide a wide FOV. The increase in the number of lenses and screens in conventional HMDs to increase the FOV do not necessarily increase the weight. But, at a minimum, appear larger and reduce their appeal to HMD users. Accordingly, improved systems and methods of providing a panoramic FOV are needed in the art.